[PATCH v5 2/4] sched/deadline: Change return value of cpudl_find()

From: Byungchul Park
Date: Mon May 22 2017 - 22:01:48 EST


Currently cpudl_find() returns the best cpu that means it has the
maximum dl, however, the value is already kept in later_mask and the
return value is not referred directly any more.

Now, it's enough to return whether CPUs were found or not, like rt.

Signed-off-by: Byungchul Park <byungchul.park@xxxxxxx>
---
kernel/sched/cpudeadline.c | 26 +++++++++++++-------------
kernel/sched/deadline.c | 6 +++---
2 files changed, 16 insertions(+), 16 deletions(-)

diff --git a/kernel/sched/cpudeadline.c b/kernel/sched/cpudeadline.c
index fba235c..7408cbe 100644
--- a/kernel/sched/cpudeadline.c
+++ b/kernel/sched/cpudeadline.c
@@ -119,29 +119,29 @@ static inline int cpudl_maximum(struct cpudl *cp)
* @p: the task
* @later_mask: a mask to fill in with the selected CPUs (or NULL)
*
- * Returns: int - best CPU (heap maximum if suitable)
+ * Returns: (int)bool - CPUs were found
*/
int cpudl_find(struct cpudl *cp, struct task_struct *p,
struct cpumask *later_mask)
{
- int best_cpu = -1;
const struct sched_dl_entity *dl_se = &p->dl;

if (later_mask &&
cpumask_and(later_mask, cp->free_cpus, &p->cpus_allowed)) {
- best_cpu = cpumask_any(later_mask);
- goto out;
- } else if (cpumask_test_cpu(cpudl_maximum(cp), &p->cpus_allowed) &&
- dl_time_before(dl_se->deadline, cp->elements[0].dl)) {
- best_cpu = cpudl_maximum(cp);
- if (later_mask)
- cpumask_set_cpu(best_cpu, later_mask);
- }
+ return 1;
+ } else {
+ int best_cpu = cpudl_maximum(cp);
+ WARN_ON(best_cpu != -1 && !cpu_present(best_cpu));

-out:
- WARN_ON(best_cpu != -1 && !cpu_present(best_cpu));
+ if (cpumask_test_cpu(best_cpu, &p->cpus_allowed) &&
+ dl_time_before(dl_se->deadline, cp->elements[0].dl)) {
+ if (later_mask)
+ cpumask_set_cpu(best_cpu, later_mask);

- return best_cpu;
+ return 1;
+ }
+ }
+ return 0;
}

/*
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 9d997d9..0223694 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -1107,7 +1107,7 @@ static void check_preempt_equal_dl(struct rq *rq, struct task_struct *p)
* let's hope p can move out.
*/
if (rq->curr->nr_cpus_allowed == 1 ||
- cpudl_find(&rq->rd->cpudl, rq->curr, NULL) == -1)
+ !cpudl_find(&rq->rd->cpudl, rq->curr, NULL))
return;

/*
@@ -1115,7 +1115,7 @@ static void check_preempt_equal_dl(struct rq *rq, struct task_struct *p)
* see if it is pushed or pulled somewhere else.
*/
if (p->nr_cpus_allowed != 1 &&
- cpudl_find(&rq->rd->cpudl, p, NULL) != -1)
+ cpudl_find(&rq->rd->cpudl, p, NULL))
return;

resched_curr(rq);
@@ -1337,7 +1337,7 @@ static int find_later_rq(struct task_struct *task)
* We have to consider system topology and task affinity
* first, then we can look for a suitable cpu.
*/
- if (cpudl_find(&task_rq(task)->rd->cpudl, task, later_mask) == -1)
+ if (!cpudl_find(&task_rq(task)->rd->cpudl, task, later_mask))
return -1;

/*
--
1.9.1